var StringBuilder = function() {
    this._string = [];
    this._delimiter = "";
    var self = this;

    this.append = function(str) {
        self._string.push(str);
        return self;
    };

    this.setDelimiter = function(del) {
        self._delimiter = del;
    };

    this.clear = function() {
        self._string = [];
    };

    this.toString = function() {
        return self._string.join(self._delimiter);
    };

    return this;
};